1. Field of the Invention
This invention relates to trash enclosures and more particularly to trash enclosures having a lid opening mechanism which includes a solenoid switch and a control circuit.
2. Previous Art
Trash enclosures may hold trash of all types. Trash may include household garbage, restaurant garbage, medical waste, chemical waste, and other industrial waste. Enclosures may partially or fully enclose trash depending on the type of trash to be enclosed. Trash enclosures often have lids which open to receive trash and close to contain odor, hide trash from view and prevent the trash from contaminating areas beyond the enclosure.
Lids are often opened by hand. Hand opened lids have several problems. In some cases, contact between a hand and the lid may spread contamination. Additionally, sometimes a free hand may not be available to open the lid.
Medical workers and food handlers, for example, may not wish to contact trash containers to avoid biological contamination. Similarly, chemical workers may not wish to contact a container such as a trash enclosure which holds chemical contaminants. Contact with any potentially contaminated container is undesirable.
In fast food restaurants, food is often served on trays. Upon finishing a meal, the trays are carried to a trash container where the trash is dumped and the tray deposited. Fast food wrappers and other waste may fly off of the tray when being dumped into the container. Two hands may be necessary to carry and dump such a tray without spilling the waste. It can be appreciated that a free hand is not always available for opening the lid and waste may spill as a result. In particular, trash may spill if the lid is not properly held open because the lid may push the trash off of the tray. This situation may be observed at many fast food restaurants which have hand operated trash enclosure lids. Such spills are sought to be avoided.
In order to facilitate insertion of trash into a trash enclosure, automatically operable lids have been developed. Such automatically operable lids may be fitted with a sensor system which automatically opens the lid upon demand. Ideally, such enclosures will eliminate the need for pushing the lid open by hand. An example an enclosure having a sensor is described in U.S. Pat. No. 4,981,275 to Sheu, the disclosure of which is incorporated herein by reference.
The Sheu invention relies upon a sensor mounted on the face of the trash enclosure. The sensor detects objects in front of the enclosure and causes the lid to open in response to detection of an object. Accordingly, a passerby may inadvertently activate the sensor and cause the lid to open. Inadvertent opening of the lid may unnecessarily release odor and contaminants from the trash enclosure. Accordingly the lid should not be inadvertently opened.
It is also known that photoelectric eyes may be employed to activate various motors or other mechanisms for opening and closing a lid. Photoelectric eyes tend to rely on visible light. When visible light is relied upon, the sun and other light sources may interfere with the operation of the sensor and, in the present case, may mistakenly or inadvertently activate the lid opening mechanism.
U.S. Pat. No. 5,932,982 which is commonly owned by the Assignee Millennium Technologies, Inc. (MTI) and is hereby incorporated by reference herein, solves inadvertent and unnecessary opening of the lid by mounting the sensor about an inner periphery of a defined bay. When an object enters the defined bay area, the sensor is activated which, in turn, activates the lid opening mechanism. As specifically mentioned in the ""982 patent, the motor unit may include a solenoid to open and close the lid which will tend to reduce the overall complexity and cost (e.g., gears motors and drive trains) of the motor unit.
However, it has been found that some solenoids may be unnecessarily noisy and may require complex design considerations to accommodate certain force characteristics required with different door characteristics (i.e., weight, inertia, timing, etc.) and to provide reliable and quiet operation. Thus, there exists a need to develop a simple, quieter, reliable and cost effective lid opening mechanism which solves some of the disadvantages known in prior devices.
The present disclosure includes a lid opening mechanism having an enclosure with at least one wall having an inner periphery which defines a bay. A lid is attached to the enclosure and is moveable between an open position and a closed position relative to the bay. A sensor activates a solenoid switch which opens the lid in response to the detection of an object within the bay. A control circuit selectively regulates the amount of electrical current to the solenoid switch.
In one embodiment of the present disclosure, the control circuit includes a microprocessor and/or a microcomputer for selectively controlling the amount of electrosurgical current supplied to the solenoid switch. Preferably, the control circuit is selectively programmable to compensate for gravitational and inertia forces acting on the lid.
In another embodiment, the solenoid switch includes a plunger which retracts a control arm to open the lid upon activation of the solenoid switch by the sensor.
In yet another embodiment, the solenoid switch includes an open limit switch and a closed limit switch. The open limit switch is preferably electrically associated with the solenoid switch to delay the electrical current to the solenoid switch for a selectively programmable period of time when the lid is in an open position. The closed limit switch is preferably electrically associated with the solenoid switch to deactivate the solenoid switch when the lid is in the closed position until the solenoid switch is activated by the sensor.
Preferably, the sensor includes an infrared photoelectric eye which generates infrared light and senses reflected infrared light to minimize sensor interference with visible light.
In one embodiment, the control circuit includes a delay which causes the lid to remain open for a predetermined period of time after the sensor activates the lid opening mechanism.